Grass weeds cause tremendous global economic losses by reducing crop yields and lowering crop values. In particular, blackgrass, barnyardgrass, ryegrass, green foxtail and wild oats cause extensive economic losses worldwide.
U.S. Pat. No. 4,225,336 discloses phenoxyalkyloxazolines which are useful as selective herbicides in cereals. U.S. Pat. No. 4,576,631 discloses certain aryloxyphenoxy oxoimidazolidines and U.S. Pat. No. 4,943,584 is directed to certain (p-Phenoxyphenoxy)-methyl-five-membered heteroaromatic compounds and their use for combatting pests. However, there remains an ongoing search in the art to create more effective and more selective herbicidal agents for the selective control of grass weeds growing in the presence of crops.
Both U.S. Pat. No. 4,750,931, which discloses herbicidal 3,5-disubstituted-2-pyridyloxy-fluorophenoxy-alkanoic acids and derivatives thereof, and U.S. Pat. No. 4,518,416, which discloses substituted pyridyl-phenyl ethers, are directed to compounds which are distinct from the compounds of the present invention.
K. Hwang and S. K. Park, Synthetic Communications, 20, pages 949-954 (1990) describe the synthesis of phenyl pyridyl ethers utilizing fluoride ion. However, the scope of the reaction is limited and high reaction temperatures are required.
It is, therefore, an object of the present invention to provide highly effective herbicidal agents useful for the selective control of grass weed species in the presence of crops.